As the size of features formed during the manufacture of a semiconductor device has shrunk, and nanometer dimensioned features have been processed, a new technology replacing conventional photolithography is needed.
As one such technology, self-assembling lithography has attracted attention. The self-assembling lithography process is a method that forms a fine pattern through phase-separation of a liquid mixture of a block copolymer applied onto a substrate. The phase-separation forms an ordered structure having nanometer scale features on a to-be-processed underlying film by removing one block polymer chain, and processing the to-be-processed film using the other block polymer chain as a mask.
As a method for controlling formation of a regular and directionally oriented ordered pattern using the natural phase-separation of the block copolymer, a directed self-assembly (DSA) technology is used, which includes forming a guide pattern on the to-be-processed film by photolithography, and applying the block copolymer onto the guide pattern. The guide pattern forms a desired order or template for developing the DSA patterns using the natural phase-separation of the block copolymer.
However, when the to-be-processed film is etched using one of the block polymer chains as a mask, amount of processing in to-be-processed film in the region which the guide pattern is formed is different from the one which the guide pattern is not formed. In this case, unevenness or roughness in the pattern is sometimes produced due to the influence of the guide pattern, for example, the roughness may be equivalent to a thickness of the guide pattern.